energy required which in this case was to grind the ore represented by the samples, from a feed size F80 of 152 mm to 80% passing 1.7 mm, and a simple adjustment procedure in case the SAG product size needed to be adjusted. Bond rod and ball mill work indices are readily converted to pinion energy for rod and ball mills but not for SAG mills.
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SAG Mill I-12 Ø Effect of SAG Mill Feed Size Distribution and Ore Variability Ø Mill liner design modifications, and Ø Circuit Design Considerations That Influenced Throughput
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Grinding or particle-size reduction is a major function of feed manufacturing. Many feed mills pass all incoming ingredients through a grinder for several reasons: (a) clumps and large fragments are reduced in size, (b) some moisture is removed due to aeration, and (c) additives such as antioxidants may be blended.
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mill work index 11.4 kWh/t and an average RQD of 44%. RQD values of 25% resulted in a SAG mill feed size (F80) between 55 and 60 mm and throughputs of 6200 t/h. RQD values of 55% resulted in SAG mill feed size (F80) of over 70 mm and a SAG mill throughput of 5200 t/h. The Batu Hijau SAG mill specific energy was a function of point load test and ...
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targets by lowering the throughput. Further, the SAG mill circuit was characterized by fluctuating feed size of between x. F, 80 =102 to 185 mm. A need for control of the feed size as well as blending ratios was recommended for an efficient operation in terms of throughput and final product size. This could be achieved through closer monitoring of
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With high aspect ratio SAG mills total charge to ball charge ratio should be greater than 2 (up to 2.5) for a coarse mill feed (say F80 > 110 mm). If the mill feed size is fine, say 50 mm or 30 mm, then you are looking at a total charge to ball charge ratio of about 1.5-1.6.
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xG is the mill feed d80, not the circuit feed. For SAG mill, the xG value has to be determined by scalping of the full size distribution. The particles larger than the minimum pebble size (given by the pebble extraction grate opening) has to be excluded …
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AG/SAG mills for a given feed size distribution and feed rate (Morrell and Morrison, 1996). Hence when using JKSimMet in a design situation, the dimensions of the AG/SAG mill are adjusted until the load in the mill reaches 25 % by volume when fed at the required feed rate. The model predicts the
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Understanding Size Effects of Semi-autogenous Grinding (SAG) Mill Operation as a Pathway to Solving Feed Disturbances - Case Study using the MMG Century SAG Mill, in Proceedings 13th AusIMM Mill Operators' Conference 2016, pp 321–330 (The Australasian Institute of Mining and Metallurgy: Melbourne)."
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A plant has four crushing stages before the material is fed into the milling circuit comprising a SAG and a Ball mill. The feed size to the first crusher is 80% passing 1,500mm with a reduction ratio of 2. The reduction ratios of the four crushing stages and that of the SAG mill are 4,5.5, 2.5, 1.8 and 1.9 respectively. i.
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F = Feed size, 80% passing (µm) f(x j) = -(0.295+x j/1000000) In 2011, Morrell discussed the appropriateness of SAG mill transfer size in regards to grinding mill specific energy modelling. It was suggested that since AG/SAG mills are mostly operated in very near 274
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Relation between Sag mill solid and product P80! Both are dependent on feed size. Dependent on Volume % solids in SAG mill. Dependent on ball charge volume. Hardness of ore. Recirculation load. Dependent on P80% size. All other parameters are secondary. In general Sag mill solids are kept at 70% by wt. Operating grinding circuit is an art.
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In this presentation an historical perspective of the origins of Mine-to-Mill is described and is followed by a discussion of how AG/SAG feed size affects throughput and specific energy and the factors that in turn influence AG/SAG …
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Figure 1 shows a range of M4A SAG feed size distributions compared with an M1 feed size distribution. It is clear that the M1 material fragments very finely in the blast …
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to a very fi ne size to allow the valuable minerals to be liberated from the surrounding ore. In a typical copper concentration plant, for example, crushed ore is fed into a SAG/Ball mill circuit with a median size of approximately 12,000 microns. Most SAG Mills are operated in closed circuit with a screen. The
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In this presentation an historical perspective of the origins of Mine-to-Mill is described and is followed by a discussion of how AG/SAG feed size affects throughput and specific energy and the factors that in turn influence AG/SAG feed size, such as ore hardness, Run of Mine (RoM) size distribution and crusher operation (both primary and secondary).
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Single stage SAG Mills are very beneficial in reducing CAPEX for plants with a staged throughput approach. When future tonnage is to be increased, the SAG Mill can feed downstream ball milling to boost capacity. Amstar SAG/AG Mills range in size from 4.3m through 12.2m in diameter with powers as high as 28,000 kW.
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In these circuits the SAG mill is the largest energy consumer. In many engineering projects either a power equation and/or a specific energy equation are used for the designing of these mills but not always with acceptable results. ... but adding a variable that represents the feed size distribution. Operational data from 4 grinding circuits ...
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The feed enters one end of the ball mill, and discharges out the other end. Ball mills vary greatly in size, from large industrial ball mills measuring more than 25 ft. in diameter to small mills used for sample preparation in laboratories. Rod mills are similar to ball mills and use metal rods as the grinding media. Pebble mills use rock ...
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• Screen capacity is influenced by aperture size, feed characteristics and screen angle; low angles increase selectivity, steep angles improve throughput. • Screens may have multiple 'decks' to split out particular size fractions. ... SAG Mill Transfer Size ...
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respect with SAG mills being increasingly less sensitive as the ball charge is increased (Morrel S and Valery W, 2001). 2.2. EFFECT OF FEED SIZE DISTRIBUTION ON SAG MILLING The qualitative effect of changes in particle size distributions (PSD) on the SAG mill performance can be addressed by using the grind curves.
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SAG mill. SAG is an acronym for semi-autogenous grinding. SAG mills are autogenous mills that also use grinding balls like a ball mill. A SAG mill is usually a primary or first stage grinder. SAG mills use a ball charge of 8 to 21%. The largest SAG mill is 42' (12.8m) in diameter, powered by a 28 MW (38,000 HP) motor.
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study focussed on ball mill limited material from the Apensu open pit. Following a benchmarking study of all blasting, crushing and grinding practices in January 2009, PTI recommended changes in both blasting and crushing conditions in order to generate a finer feed size to the SAG mill.
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Hardest measurements were used to allow any blend of feed to be treated at design t/h. A total of 9 kWh/t of grinding energy was indicated and this could be provided either in a single stage SAG mill to produce the P80 200 micron product, or a two stage circuit with equal power on the SAG and ball mills using the design Bond Wi of 11.5 kWh/t.
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Introduction. The residual feed intake (RFI) and residual intake and gain (RIG) are two indices to measure the feed efficiency of livestock. They have become popular in recent decades because they are independent of body size and productivity (Koch et al. 1963; Berry and Crowley 2012).Both indices have become alternative measures applied to improve the profitability of …
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While AG mills operate without a ball charge, SAG mills use a grinding media charge of normally 3 % - 12 % for comminuting the feed material. The maximum feed size is between 200 mm and 500 mm. The AG/SAG mill is normally installed upstream of a tube mill operating in closed circuit with hydrocyclones.
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When the feed size of a SAG mill becomes coarser, i.e. α r increases, the energy required to break the ore increases, i.e. φ r and φ f increases (Morrell et al., …
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Although it is well known and easily experienced that the feed size distribution influences the throughput and stability of operation of a semi-autogenous grinding (SAG) mill, the details are poorly understood since it is often only the input and output measurements that are used to identify unfavourable in-mill conditions. Load cells and power monitoring are sometimes used …
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The optimum feed size for the rod mill oversize feed factor (EF 4 RM) in the Barratt E SAG equation is calculated using the greater of the sample's rod mill or crushing work index. The EF 4 RM is calculated greater of the crushing work index or the rod mill work index. The ball mill oversize feed factor (EF 4 BM) is always calculated with the ...
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Rod mill：The rod mill has the highest efficiency when the feed size is <30mm and the discharge size is about 3mm with uniform particle size and light overcrushing phenomenon. SAG mill: When the weight of the SAG mill is more than 75%, the output is high and the energy consumption is low with a light degree of over-crushing.
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Morrell and Valery Jnr., W. (2001) Influence of Feed Size on AG/SAG Mill Performance. SAG2001 - SAG mill circuit. International Conference on Autogenous and Semiautogenous
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The purpose of the primary crusher is to reduce the ROM ore to a size amenable for feeding the secondary crusher or the SAG mill grinding circuit. The ratio of reduction through a primary crusher can be up to about 8:1. Feed: ROM up to 1.5 m; Product: -300mm (for transport) to -200mm (for SAG mill) Feed Rate: 160 to 13,000 tph
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In Fig. 3, Fig. 4 the data is presented in order to show the effect of the fresh feed size, particularly the % −6″ +1″ (−152 +25 mm), on the SAG mill power consumption (Pc) in kW and on the SAG mill specific energy consumption (Ecs) in kW h/t, obtained by dividing the power consumed (kW) by the fresh feed rate (t/h).
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Fo - Optimum Feed Size for rod mills F o W r =16 000 ... size and power relationships For SAG mills the equation becomes Power=(5.6115+%balls*0.1438)*D24. 6* L Mill Critical speed Crit Crit D = 42.3 n - revs per min nC= s*Crit Cs is the fraction of the critical speed
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The oversize crusher feed size distribution, oscf, and the primary cyclone feed size distribution, pcfd, are estimated utilising the SAG mill grate size and discharge screen aperture sizes and the Rosin-Rammler size distribution function, which has been selected for its convenience and since it "has been found to fit many
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